Phenol can be selectively alkylated in an ortho position following the pioneering discovery of Ecke and Kolka, U.S. Pat. No. 2,831,898 . According to U.S. Pat. No. '898, phenol containing an aluminum phenoxide is reacted with olefin at elevated temperature to produce an alkylation mixture containing substantial amounts of 2-alkylphenol and 2,6-dialkylphenol as well as other isomers.
Coffield et al., U.S. Pat. No. 3,355,504, describe an improvement in the orthoalkylation process wherein 2,6-di-alkylphenols are made in high yield under moderate conditions by starting the process with 2-alkylphenol containing an aluminum 2-alkylphenoxide and reacting this mixture with an olefin. If the 2-alkylphenol is made by the aluminum phenoxide catalyzed alkylation of phenol, then additional aluminum phenoxide forming compound must be added to be in molar excess of any remaining phenol or phenol ethers before conducting the second alkylation.